PP1773_unit_alt_grid is a polygon shapefile of surface altitudes for 16 hydrogeologic units as described in report Professional Paper 1773. Surface altitudes were interpolated and discretized to the 2-mile by 2-mile rotated grid used to simulate groundwater flow in the Atlantic Coastal Plain of North and South Carolina. Altitudes are available for 17 surfaces, hydrogeologic unit layer 1 (top - land surface) through Layer 16 (top and bottom). Each hydrogeologic unit is referred to as its model layer number as represented in the report PP1773. For clarity, they are listed below along with the aquifer unit or confining unit name in North Carolina and its correlated name in South Carolina L1 Surficial aquifer L2 Yorktown confining unit / Upper Floridan confining unit L3 Yorktown aquifer / Upper Floridan aquifer L4 Castle Hayne - Pungo River confining unit / Middle Floridan confining unit (To be referred to as "Castle Hayne confining unit / Middle Floridan confining unit" in this document) L5 Castle Hayne - Pungo River aquifer / Middle Floridan aquifer (To be referred to as "Castle Hayne aquifer / Middle Floridan aquifer" in this document) L6 Beaufort confining unit / Gordon confining unit L7 Beaufort aquifer / Gordon aquifer L8 Peedee confining unit / Crouch Branch confining unit L9 Peedee aquifer / Crouch Branch aquifer L10 Black Creek confining unit / McQueen Branch confining unit L11 Black Creek aquifer / McQueen Branch aquifer L12 Upper Cape Fear confining unit / Charleston confining unit L13 Upper Cape Fear aquifer / Charleston aquifer L14 Lower Cape Fear confining unit / Gramling confining unit L15 Lower Cape Fear aquifer / Gramling aquifer L16 Lower Cretaceous confining unit and aquifer

PP1773_unit_alt_grid is a polygon shapefile of surface altitudes for 16 hydrogeologic units as described in report Professional Paper 1773. Surface altitudes were interpolated and discretized to the 2-mile by 2-mile rotated grid used to simulate groundwater flow in the Atlantic Coastal Plain of North and South Carolina. Altitudes are available for 17 surfaces, hydrogeologic unit layer 1 (top - land surface) through Layer 16 (top and bottom). Each hydrogeologic unit is referred to as its model layer number as represented in the report PP1773. For clarity, they are listed below along with the aquifer unit or confining unit name in North Carolina and its correlated name in South Carolina L1 Surficial aquifer L2 Yorktown confining unit / Upper Floridan confining unit L3 Yorktown aquifer / Upper Floridan aquifer L4 Castle Hayne - Pungo River confining unit / Middle Floridan confining unit (To be referred to as "Castle Hayne confining unit / Middle Floridan confining unit" in this document) L5 Castle Hayne - Pungo River aquifer / Middle Floridan aquifer (To be referred to as "Castle Hayne aquifer / Middle Floridan aquifer" in this document) L6 Beaufort confining unit / Gordon confining unit L7 Beaufort aquifer / Gordon aquifer L8 Peedee confining unit / Crouch Branch confining unit L9 Peedee aquifer / Crouch Branch aquifer L10 Black Creek confining unit / McQueen Branch confining unit L11 Black Creek aquifer / McQueen Branch aquifer L12 Upper Cape Fear confining unit / Charleston confining unit L13 Upper Cape Fear aquifer / Charleston aquifer L14 Lower Cape Fear confining unit / Gramling confining unit L15 Lower Cape Fear aquifer / Gramling aquifer L16 Lower Cretaceous confining unit and aquifer

A hydrogeologic framework was developed by USGS during 2016-19 to describe the groundwater system on the Virginia Eastern Shore. This USGS data release contains text files of (1) interpreted borehole hydrogeologic-unit top-surface altitudes, (2) summary values of previously documented estimates of aquifer hydraulic properties, and (3) groundwater-sample chloride concentrations and well summary statistics. In addition are shapefiles of altitude contours for 10 hydrogeologic-unit top surfaces, and for the groundwater 250 milligrams per liter chloride-concentration surface. This data release supports the following publication: McFarland, E.R., and Beach, T.A., 2019, Hydrogeologic framework of the Virginia Eastern Shore: U.S. Geological Survey Scientific Investigations Report 2019-5093, 26 p., 13 pl., https://doi.org/10.3133/sir20195093.

A hydrogeologic framework was developed by USGS during 2016-19 to describe the groundwater system on the Virginia Eastern Shore. This USGS data release contains text files of (1) interpreted borehole hydrogeologic-unit top-surface altitudes, (2) summary values of previously documented estimates of aquifer hydraulic properties, and (3) groundwater-sample chloride concentrations and well summary statistics. In addition are shapefiles of altitude contours for 10 hydrogeologic-unit top surfaces, and for the groundwater 250 milligrams per liter chloride-concentration surface. This data release supports the following publication: McFarland, E.R., and Beach, T.A., 2019, Hydrogeologic framework of the Virginia Eastern Shore: U.S. Geological Survey Scientific Investigations Report 2019-5093, 26 p., 13 pl., https://doi.org/10.3133/sir20195093.

A hydrogeologic framework of the Ozark Plateaus aquifer system was constructed as the base for a groundwater flow model developed as part of the U.S. Geological Survey Water Availability and Use Science Program to aid in the understanding of groundwater availability in select aquifer systems of the United States. The Ozark Plateaus aquifer system study area (hereinafter referred to as the “Ozark system”) is nearly 70,000 square miles and includes parts of Arkansas, Kansas, Missouri, and Oklahoma. A hydrogeologic framework was constructed to represent the altitudes and thicknesses of nine hydrogeologic units within the Ozark Plateaus aquifer system - . the Western Interior Plains confining system, Springfield Plateau aquifer, the Ozark confining unit, Ozark aquifer (divided into the upper, middle, and lower Ozark aquifers to better capture the spatial variation in the hydrologic properties), the St. Francois confining unit, the St. Francois aquifer, and the Basement confining unit. The formations that make up the hydrogeologic units of the Ozark system range from Pennsylvanian to Cambrian age. The scope of effort included the compilation and interpretation of hydrogeologic altitudes from geophysical, lithologic driller description, and well cutting logs. The final compiled dataset included more than 23,000 individual altitude points (excluding synthetic points) representing the nine hydrogeologic units. Shorthand names were used to identify points, extents, and raster surfaces corresponding to each hydrogeologic unit. WIPCS = Western Interior Plains confining system SPA = Springfield Plateau aquifer OCU = Ozark confining unit UOA = upper Ozark aquifer MOA = middle Ozark aquifer LOA = lower Ozark aquifer SFCU = St. Francois confining unit SFA = St. Francois aquifer BCU = basement confining unit

A hydrogeologic framework of the Ozark Plateaus aquifer system was constructed as the base for a groundwater flow model developed as part of the U.S. Geological Survey Water Availability and Use Science Program to aid in the understanding of groundwater availability in select aquifer systems of the United States. The Ozark Plateaus aquifer system study area (hereinafter referred to as the “Ozark system”) is nearly 70,000 square miles and includes parts of Arkansas, Kansas, Missouri, and Oklahoma. A hydrogeologic framework was constructed to represent the altitudes and thicknesses of nine hydrogeologic units within the Ozark Plateaus aquifer system - . the Western Interior Plains confining system, Springfield Plateau aquifer, the Ozark confining unit, Ozark aquifer (divided into the upper, middle, and lower Ozark aquifers to better capture the spatial variation in the hydrologic properties), the St. Francois confining unit, the St. Francois aquifer, and the Basement confining unit. The formations that make up the hydrogeologic units of the Ozark system range from Pennsylvanian to Cambrian age. The scope of effort included the compilation and interpretation of hydrogeologic altitudes from geophysical, lithologic driller description, and well cutting logs. The final compiled dataset included more than 23,000 individual altitude points (excluding synthetic points) representing the nine hydrogeologic units. Shorthand names were used to identify points, extents, and raster surfaces corresponding to each hydrogeologic unit. WIPCS = Western Interior Plains confining system SPA = Springfield Plateau aquifer OCU = Ozark confining unit UOA = upper Ozark aquifer MOA = middle Ozark aquifer LOA = lower Ozark aquifer SFCU = St. Francois confining unit SFA = St. Francois aquifer BCU = basement confining unit

The data set pp1773_extents contains polygon datasets that represent the areal extents of each of the 16 hydrogeologic units of the of the Atlantic Coastal Plain of North and South Carolina. [The total areal extent includes a small area in southeastern Virginia, the Atlantic Coastal Plain within North Carolina and South Carolina, and a region in southeast Georgia within the Atlantic Coastal Plain.] Each hydrogeological unit is referred to as its model layer number as represented in the report PP1773. For clarity, they are listed below along with the aquifer unit or confining unit name in North Carolina and its correlated unit name in South Carolina. L1 Surficial aquifer L2 Yorktown confining unit / Upper Floridan confining unit L3 Yorktown aquifer / Upper Floridan aquifer L4 Castle Hayne - Pungo River confining unit / Middle Floridan confining unit (To be referred to as "Castle Hayne / Middle Floridan confining unit" in this document) L5 Castle Hayne - Pungo River aquifer / Middle Floridan aquifer (To be referred to as "Castle Hayne - Middle Floridan aquifer" in this document) L6 Beaufort confing unit / Gordon confining unit L7 Beaufort aquifer / Gordon aquifer L8 Peedee confining unit / Crouch Branch confining unit L9 Peedee aquifer / Crouch Branch aquifer L10 Black Creek confining unit / McQueen Branch confining unit L11 Black Creek aquifer / McQueen Branch aquifer L12 Upper Cape Fear confining unit / Charleston confining unit L13 Upper Cape Fear aquifer / Charleston aquifer L14 Lower Cape Fear confining unit / Gramling confining unit L15 Lower Cape Fear aquifer / Gramling aquifer L16 Lower Cretaceous confining unit and aquifer Spatial data set pp1773_layer1_extent represents the extent of the top of the surficial aquifer, which is Layer 1 in the groundwater model used to simulate the aquifer system described in PP 1773. The surficial aquifer is the uppermost aquifer. It is an unconfined aquifer that is uniformly present except where it is incised by streams. The top of the surficial aquifer is equivalent to the land surface. The extent was derived primarily by geologic and hydraulic properties, as the surficial aquifer is an unconfined layer primarily composed of sediments of Quaternary age, plus some older sediments in areas due to a different stratigraphic position of the first underlying confining layer. Spatial data set pp_1773_layer_2 is the Yorktown/Upper Floridan confining unit. It is not composed of a single unit because the unit's series of clay and silt beds vary greatly in stratigraphic position. Spatial dataset pp1773_layer3_extent represents the extent of the Yorktown/Upper Floridan aquifer. The Yorktown aquifer is present only in the northern half of the North Carolina Coastal Plain. Outliers exist in Robeson, Bladen and Dublin counties, but are not separated from the surficial aquifer by a confining unit, and not considered a distinct aquifer in these areas. The Upper Floridan aquifer extent covers a southern portion of South Carolina and southern portion of Georgia. Spatial dataset pp1773_layer4_extent represents the extent of the Castle Hayne/Middle Floridan confining unit. The Castle Hayne confining unit consists of beds of clay and silt that vary in stratigraphic position and are absent in a number of areas in the central and southern North Carolina Coastal Plain. The Middle Floridan confining unit extends from South Carolina to southern Georgia. It is not continuous with the Castle Hayne confining unit. Spatial dataset pp1773_layer5_extent represents the extent of the Castle Hayne/Middle Floridan aquifer. The Castle Hayne aquifer is located in the central and southern North Carolina Coastal Plain; the Middle Floridan aquifer is more south, in southern South Carolina and southern Georgia. Spatial dataset pp1773_layer6_extent represents the extent of the Beaufort/Gordon confining unit. The Beaufort confining unit is located in northeastern North Carolina and southeastern Virginia. It is best developed in

The data set pp1773_extents contains polygon datasets that represent the areal extents of each of the 16 hydrogeologic units of the of the Atlantic Coastal Plain of North and South Carolina. [The total areal extent includes a small area in southeastern Virginia, the Atlantic Coastal Plain within North Carolina and South Carolina, and a region in southeast Georgia within the Atlantic Coastal Plain.] Each hydrogeological unit is referred to as its model layer number as represented in the report PP1773. For clarity, they are listed below along with the aquifer unit or confining unit name in North Carolina and its correlated unit name in South Carolina. L1 Surficial aquifer L2 Yorktown confining unit / Upper Floridan confining unit L3 Yorktown aquifer / Upper Floridan aquifer L4 Castle Hayne - Pungo River confining unit / Middle Floridan confining unit (To be referred to as "Castle Hayne / Middle Floridan confining unit" in this document) L5 Castle Hayne - Pungo River aquifer / Middle Floridan aquifer (To be referred to as "Castle Hayne - Middle Floridan aquifer" in this document) L6 Beaufort confing unit / Gordon confining unit L7 Beaufort aquifer / Gordon aquifer L8 Peedee confining unit / Crouch Branch confining unit L9 Peedee aquifer / Crouch Branch aquifer L10 Black Creek confining unit / McQueen Branch confining unit L11 Black Creek aquifer / McQueen Branch aquifer L12 Upper Cape Fear confining unit / Charleston confining unit L13 Upper Cape Fear aquifer / Charleston aquifer L14 Lower Cape Fear confining unit / Gramling confining unit L15 Lower Cape Fear aquifer / Gramling aquifer L16 Lower Cretaceous confining unit and aquifer Spatial data set pp1773_layer1_extent represents the extent of the top of the surficial aquifer, which is Layer 1 in the groundwater model used to simulate the aquifer system described in PP 1773. The surficial aquifer is the uppermost aquifer. It is an unconfined aquifer that is uniformly present except where it is incised by streams. The top of the surficial aquifer is equivalent to the land surface. The extent was derived primarily by geologic and hydraulic properties, as the surficial aquifer is an unconfined layer primarily composed of sediments of Quaternary age, plus some older sediments in areas due to a different stratigraphic position of the first underlying confining layer. Spatial data set pp_1773_layer_2 is the Yorktown/Upper Floridan confining unit. It is not composed of a single unit because the unit's series of clay and silt beds vary greatly in stratigraphic position. Spatial dataset pp1773_layer3_extent represents the extent of the Yorktown/Upper Floridan aquifer. The Yorktown aquifer is present only in the northern half of the North Carolina Coastal Plain. Outliers exist in Robeson, Bladen and Dublin counties, but are not separated from the surficial aquifer by a confining unit, and not considered a distinct aquifer in these areas. The Upper Floridan aquifer extent covers a southern portion of South Carolina and southern portion of Georgia. Spatial dataset pp1773_layer4_extent represents the extent of the Castle Hayne/Middle Floridan confining unit. The Castle Hayne confining unit consists of beds of clay and silt that vary in stratigraphic position and are absent in a number of areas in the central and southern North Carolina Coastal Plain. The Middle Floridan confining unit extends from South Carolina to southern Georgia. It is not continuous with the Castle Hayne confining unit. Spatial dataset pp1773_layer5_extent represents the extent of the Castle Hayne/Middle Floridan aquifer. The Castle Hayne aquifer is located in the central and southern North Carolina Coastal Plain; the Middle Floridan aquifer is more south, in southern South Carolina and southern Georgia. Spatial dataset pp1773_layer6_extent represents the extent of the Beaufort/Gordon confining unit. The Beaufort confining unit is located in northeastern North Carolina and southeastern Virginia. It is best developed in

In 1999, the USGS, in partnership with the South Carolina Sea Grant Consortium, began a study to investigate processes affecting shoreline change along the northern coast of South Carolina, focusing on the Grand Strand region. Previous work along the U.S. Atlantic coast shows that the structure and composition of older geologic strata located seaward of the coast heavily influences the coastal behavior of areas with limited sediment supply, such as the Grand Strand. By defining this geologic framework and identifying the transport pathways and sinks of sediment, geoscientists are developing conceptual models of the present-day physical processes shaping the South Carolina coast. The primary objectives of this research effort are: 1) to provide a regional synthesis of the shallow geologic framework underlying the coastal upland, shoreface and inner continental shelf, and define its role in coastal evolution and modern beach behavior; 2) to identify and model the physical processes affecting coastal ocean circulation and sediment transport, and to define their role in shaping the modern shoreline; and 3) to identify sediment sources and transport pathways; leading to construction of a regional sediment budget.

In 1999, the USGS, in partnership with the South Carolina Sea Grant Consortium, began a study to investigate processes affecting shoreline change along the northern coast of South Carolina, focusing on the Grand Strand region. Previous work along the U.S. Atlantic coast shows that the structure and composition of older geologic strata located seaward of the coast heavily influences the coastal behavior of areas with limited sediment supply, such as the Grand Strand. By defining this geologic framework and identifying the transport pathways and sinks of sediment, geoscientists are developing conceptual models of the present-day physical processes shaping the South Carolina coast. The primary objectives of this research effort are: 1) to provide a regional synthesis of the shallow geologic framework underlying the coastal upland, shoreface and inner continental shelf, and define its role in coastal evolution and modern beach behavior; 2) to identify and model the physical processes affecting coastal ocean circulation and sediment transport, and to define their role in shaping the modern shoreline; and 3) to identify sediment sources and transport pathways; leading to construction of a regional sediment budget.